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freebsd-nq/lib/libc/sys/aio_fsync.2

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Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.\" Copyright (c) 2013 Sergey Kandaurov
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" $FreeBSD$
.\"
Fix various nits in the aio operation manpages. - Avoid double use of "request" in a single sentence. Instead, describe aio_sigevent as being used to request notification of the associated operation's completion. This matches the language used to describe aio_sigevent in aio(4). - Simplify the prohibition on modifying buffers while requests are in flight. - Fix case mismatch. - Drop note about not using stack variables. C programmers should be able to figure out if a stack variable is safe based on the later warning about the life cycle requirements of control blocks. - Remove prohibition on modifying the I/O buffer for aio_fsync() since it does not use an I/O buffer. For aio_mlock(), prohibit modifications to the mapping (e.g. due to mprotect, munmap, mmap, etc.) but do not prohibit modifications to the memory backing the buffer (stores into the pages backing the buffer). Requested by: wblock (1,2), kib (4) Reviewed by: kib, rpokala, wblock MFC after: 3 days Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D7462
2016-08-19 17:37:32 +00:00
.Dd August 19, 2016
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.Dt AIO_FSYNC 2
.Os
.Sh NAME
.Nm aio_fsync
.Nd asynchronous file synchronization (REALTIME)
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In aio.h
.Ft int
.Fn aio_fsync "int op" "struct aiocb *iocb"
.Sh DESCRIPTION
The
.Fn aio_fsync
system call allows the calling process to move all modified data
associated with the descriptor
.Fa iocb->aio_fildes
to a permanent storage device.
The call returns immediately after the synchronization request has been
enqueued to the descriptor; the synchronization may or may not have
completed at the time the call returns.
.Pp
The
.Fa op
- Fix EBADF description, in following the future POSIX tc and what FreeBSD actually implements. - Improve grammar: use more preferred "can", not "could". Submitted by: jilles
2013-12-27 16:57:38 +00:00
argument can only be set to
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.Dv O_SYNC
to cause all currently queued I/O operations to be completed
as if by a call to
.Xr fsync 2 .
.Pp
If _POSIX_PRIORITIZED_IO is defined, and the descriptor supports it,
then the enqueued operation is submitted at a priority equal to that
of the calling process minus
.Fa iocb->aio_reqprio .
.Pp
The
.Fa iocb
pointer may be subsequently used as an argument to
.Fn aio_return
and
.Fn aio_error
in order to determine return or error status for the enqueued operation
while it is in progress.
.Pp
If the request could not be enqueued (generally due to invalid arguments),
the call returns without having enqueued the request.
Add documentation for the sigevent structure. - Add a sigevent(3) manpage to give a general overview of the sigevent structure and the available notification mechanisms. - Document that AIO requests contain a nested sigevent structure that can be used to request completion notification. - Expand the sigevent details in other manuals to note details such as the extra values stored in a queued signal's information or in a posted kevent. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
2016-07-15 15:12:56 +00:00
.Pp
The
.Fa iocb->aio_sigevent
Fix various nits in the aio operation manpages. - Avoid double use of "request" in a single sentence. Instead, describe aio_sigevent as being used to request notification of the associated operation's completion. This matches the language used to describe aio_sigevent in aio(4). - Simplify the prohibition on modifying buffers while requests are in flight. - Fix case mismatch. - Drop note about not using stack variables. C programmers should be able to figure out if a stack variable is safe based on the later warning about the life cycle requirements of control blocks. - Remove prohibition on modifying the I/O buffer for aio_fsync() since it does not use an I/O buffer. For aio_mlock(), prohibit modifications to the mapping (e.g. due to mprotect, munmap, mmap, etc.) but do not prohibit modifications to the memory backing the buffer (stores into the pages backing the buffer). Requested by: wblock (1,2), kib (4) Reviewed by: kib, rpokala, wblock MFC after: 3 days Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D7462
2016-08-19 17:37:32 +00:00
structure can be used to request notification of the operation's
Add documentation for the sigevent structure. - Add a sigevent(3) manpage to give a general overview of the sigevent structure and the available notification mechanisms. - Document that AIO requests contain a nested sigevent structure that can be used to request completion notification. - Expand the sigevent details in other manuals to note details such as the extra values stored in a queued signal's information or in a posted kevent. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
2016-07-15 15:12:56 +00:00
completion as described in
.Xr aio 4 .
.Sh RESTRICTIONS
Fix various nits in the aio operation manpages. - Avoid double use of "request" in a single sentence. Instead, describe aio_sigevent as being used to request notification of the associated operation's completion. This matches the language used to describe aio_sigevent in aio(4). - Simplify the prohibition on modifying buffers while requests are in flight. - Fix case mismatch. - Drop note about not using stack variables. C programmers should be able to figure out if a stack variable is safe based on the later warning about the life cycle requirements of control blocks. - Remove prohibition on modifying the I/O buffer for aio_fsync() since it does not use an I/O buffer. For aio_mlock(), prohibit modifications to the mapping (e.g. due to mprotect, munmap, mmap, etc.) but do not prohibit modifications to the memory backing the buffer (stores into the pages backing the buffer). Requested by: wblock (1,2), kib (4) Reviewed by: kib, rpokala, wblock MFC after: 3 days Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D7462
2016-08-19 17:37:32 +00:00
The Asynchronous I/O Control Block structure pointed to by
Add documentation for the sigevent structure. - Add a sigevent(3) manpage to give a general overview of the sigevent structure and the available notification mechanisms. - Document that AIO requests contain a nested sigevent structure that can be used to request completion notification. - Expand the sigevent details in other manuals to note details such as the extra values stored in a queued signal's information or in a posted kevent. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
2016-07-15 15:12:56 +00:00
.Fa iocb
must remain valid until the
operation has completed.
.Pp
The asynchronous I/O control buffer
.Fa iocb
should be zeroed before the
.Fn aio_fsync
call to avoid passing bogus context information to the kernel.
.Pp
Fix various nits in the aio operation manpages. - Avoid double use of "request" in a single sentence. Instead, describe aio_sigevent as being used to request notification of the associated operation's completion. This matches the language used to describe aio_sigevent in aio(4). - Simplify the prohibition on modifying buffers while requests are in flight. - Fix case mismatch. - Drop note about not using stack variables. C programmers should be able to figure out if a stack variable is safe based on the later warning about the life cycle requirements of control blocks. - Remove prohibition on modifying the I/O buffer for aio_fsync() since it does not use an I/O buffer. For aio_mlock(), prohibit modifications to the mapping (e.g. due to mprotect, munmap, mmap, etc.) but do not prohibit modifications to the memory backing the buffer (stores into the pages backing the buffer). Requested by: wblock (1,2), kib (4) Reviewed by: kib, rpokala, wblock MFC after: 3 days Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D7462
2016-08-19 17:37:32 +00:00
Modification of the Asynchronous I/O Control Block structure is not allowed
while the request is queued.
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.Sh RETURN VALUES
.Rv -std aio_fsync
.Sh ERRORS
The
.Fn aio_fsync
system call will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
The request was not queued because of system resource limitations.
Add documentation for the sigevent structure. - Add a sigevent(3) manpage to give a general overview of the sigevent structure and the available notification mechanisms. - Document that AIO requests contain a nested sigevent structure that can be used to request completion notification. - Expand the sigevent details in other manuals to note details such as the extra values stored in a queued signal's information or in a posted kevent. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
2016-07-15 15:12:56 +00:00
.It Bq Er EINVAL
The asynchronous notification method in
.Fa iocb->aio_sigevent.sigev_notify
is invalid or not supported.
Add more documentation regarding unsafe AIO requests. The asynchronous I/O changes made previously result in different behavior out of the box. Previously all AIO requests failed with ENOSYS / SIGSYS unless aio.ko was explicitly loaded. Now, some AIO requests complete and others ("unsafe" requests) fail with EOPNOTSUPP. Reword the introductory paragraph in aio(4) to add a general description of AIO before describing the vfs.aio.enable_unsafe sysctl. Remove the ENOSYS error description from aio_fsync(2), aio_read(2), and aio_write(2) and replace it with a description of EOPNOTSUPP. Remove the ENOSYS error description from aio_mlock(2). Log a message to the system log the first time a process requests an "unsafe" AIO request that fails with EOPNOTSUPP. This is modeled on the log message used for processes using the legacy pty devices. Reviewed by: kib (earlier version) MFC after: 1 week Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D7151
2016-07-21 22:49:47 +00:00
.It Bq Er EOPNOTSUPP
Asynchronous file synchronization operations on the file descriptor
.Fa iocb->aio_fildes
are unsafe and unsafe asynchronous I/O operations are disabled.
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.It Bq Er EINVAL
A value of the
.Fa op
argument is not set to
.Dv O_SYNC .
.El
.Pp
The following conditions may be synchronously detected when the
.Fn aio_fsync
system call is made, or asynchronously, at any time thereafter.
If they are detected at call time,
.Fn aio_fsync
returns -1 and sets
.Va errno
appropriately; otherwise the
.Fn aio_return
system call must be called, and will return -1, and
.Fn aio_error
must be called to determine the actual value that would have been
returned in
.Va errno .
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa iocb->aio_fildes
- Fix EBADF description, in following the future POSIX tc and what FreeBSD actually implements. - Improve grammar: use more preferred "can", not "could". Submitted by: jilles
2013-12-27 16:57:38 +00:00
argument
is not a valid descriptor.
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.It Bq Er EINVAL
This implementation does not support synchronized I/O for this file.
.El
.Pp
If the request is successfully enqueued, but subsequently cancelled
or an error occurs, the value returned by the
.Fn aio_return
system call is per the
.Xr read 2
and
.Xr write 2
system calls, and the value returned by the
.Fn aio_error
system call is one of the error returns from the
.Xr read 2
or
.Xr write 2
system calls.
.Sh SEE ALSO
.Xr aio_cancel 2 ,
.Xr aio_error 2 ,
.Xr aio_read 2 ,
.Xr aio_return 2 ,
.Xr aio_suspend 2 ,
.Xr aio_waitcomplete 2 ,
.Xr aio_write 2 ,
.Xr fsync 2 ,
Add documentation for the sigevent structure. - Add a sigevent(3) manpage to give a general overview of the sigevent structure and the available notification mechanisms. - Document that AIO requests contain a nested sigevent structure that can be used to request completion notification. - Expand the sigevent details in other manuals to note details such as the extra values stored in a queued signal's information or in a posted kevent. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
2016-07-15 15:12:56 +00:00
.Xr sigevent 3 ,
Provide the manual page for aio_fsync(2). Reviewed by: davidxu MFC after: 1 week
2013-12-26 19:16:30 +00:00
.Xr siginfo 3 ,
.Xr aio 4
.Sh STANDARDS
The
.Fn aio_fsync
system call is expected to conform to the
.St -p1003.1
standard.
.Sh HISTORY
The
.Fn aio_fsync
system call first appeared in
.Fx 7.0 .
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